Subject: Yellow-bellied duff runner? Northern MN
Location: Superior National Forest, Minnesota
August 13, 2012 5:38 pm
I work on the Superior National Forest in northern Minnesota and during the past few summers have continued to come across this peculiar insect. It has six legs, appears to have chewing mouth parts, is usually about 1” long, and has hidden wings. It flies around the understory in mixed hardwood forests, landing on leaves/stems and drops into the duff and runs off quite quickly whenever I get too close. The underside of it’s abdomen is bright yellow, and I’ve seen several specimens twitch and raise the tip of the abdomen (ovipositors?) almost menacingly. It’s such a bizarre insect I have no clue where to start with ID. So far, I’ve been calling them ”yellow-bellied duff runners”, but would love to know what they actually are! Thanks in advance for your help!
As much as we love the name you have coined, Yellow Bellied Duff Runner, the real name for this unusual beetle is the Gold and Brown Rove Beetle, Ontholestes cingulatus. According to BugGuide: “Adults eat maggots, mites, beetle larvae. Larvae feed on carrion, fungi” and “Eggs are laid near carrion or fungi. Larvae feed on carrion or fungi, presumably. Pupate in chambers in soil nearby. Given the collection dates of spring and fall, it seems likely that they overwinter as adults.” The individuals you observed sound like they were searching for food. This large Rove Beetle, like most of its relatives, is perfectly harmless despite the menacing posture it strikes when threatened. There is a group of Rove Beetles, though, known as the Paederus Rove Beetles in most parts of the world or Creechie Bugs in Africa that can cause a nasty case of contact dermatitis. The Paederus Rove Beetles sport aposomatic or warning coloration in bold patterns of orange and black.